These three series of talks given by Wilfred Bion are edited versions of spontaneous contributions and discussions with groups in New York, São Paulo and at the Tavistock Clinic, London, where Martha Harris invited him to return and give annual talks after he had moved to California. In these informal settings, each with their own distinctive  group atmosphere, Bion expressed his most evolved thinking about thinking. As Martha Harris put it: ‘Thinking he regarded as a human activity still in its absolute infancy. The development of a capacity to think creatively, which might harness human passions in the service of development and wisdom, appeared to him as something of a race against time.’ In these talks there is an opportunity to meet ‘the Bion who sees analysis in the consulting room not as a refuge, but as a preparation for the real thing: for a richer and wiser mode of living in the world’ (Martha Harris’ obituary of Bion).